Generally, quantum key distribution (QKD) systems are employed for applications that require higher levels of cryptographic security than available from more standard cryptographic systems, such as when it's desired to secure communicated data against analysis from possible computational advances in the future. As such, QKD systems are of interest to information security for government, banking, and other markets. However, the current market for QKD systems is limited by the small range or low speed in single-channel commercial products.
Additionally, free-space quantum communication has had limited application, as transmission lengths in the atmosphere are much smaller than in silica fiber at telecommunication wavelengths. Due in part to the fact that the speed of secure quantum communication in free space drops significantly with distance, free-space quantum communication systems have garnered little attention to date.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore it may contain information that does not form the prior art.